The present invention relates to metallurgy, and more particularly to methods of reduction of an oxidized surface of metals.
Known in the prior art is a method of cleansing an oxidized surface of copper by etching. (I. D. Troitsky et al., "Proizvodstvo Elektricheskikh Kabelei i Provodov s Rezinoplastmassovoi Izolyatsijei" (Manufacturing of Electrical Cables and Wires with Rubberized Plastic Insulation), "Vysshaya Shkola" Publishers, Moscow, 1967, p. 77).
According to this method, a partial reduction of metal takes place when etching an oxidized surface of copper in a solution of sulphuric acid.
Hot working of metals results in the formation of a layer of metal oxides. Being of a high hardness and brittleness, this layer impairs conditions for the further cold working of the metal. In drawing, it is likely to increase wearing of dies, draw plates, and to choke up the drawing machine. In the process of cold rolling, there results an increase in wearing of rolls, and clogging of rolling stands with dust is inevitable. The formation of dust in the process of cold working is conducive to irretrievable losses of metal with this dust, and is likely to set up unfavorable conditions for the working personnel.
In the process of cable-manufacturing, the oxidized layer detrimentally affects the adhesive capacity of insulating materials to metal.
At the present time, the surface of the metal is cleaned of oxides by the etching process. For this purpose, etching departments are provided in factories. Etching involves the consumption of acid and soda, employment of additional equipment and special attendants. The etching process involves dissolution of copper whose recovery is connected with a number of difficulties.
To carry out etching requires loose winding (in a coil) of rolled wire or rods of a great length with a view to ensuring the penetration of the acid inside the coil, followed by washing off the copper dust reduced from oxides in the etching process.